The invention relates to a humic acid-containing concentrated liquid compound fertilizer and a preparation method thereof. The humic acid-containing concentrated liquid compound fertilizer consists of humic acid, urea, potassium sulfate, potassium dihydrogen phosphate, phosphoric acid, ammonia, potassium nitrate, organic chelating rare earth and tap water. The preparation method of the humic acid-containing concentrated liquid compound fertilizer comprises the following steps of: firstly weighing the tap water according to a weight ratio, and putting the tap water in a reaction kettle; after the beginning of mixing and heating, weighing the humic acid, the urea, the potassium sulfate, the potassium dihydrogen phosphate, the phosphoric acid, the ammonia, the potassium nitrate and the organic chelating rare earth for standby according to the weight ratio, and putting the materials in the reaction kettle; mixing and heating to 50 DEG C to 60 DEG C, keeping for 2 hours to 3 hours, and cooling to 25 DEG C to 40 DEG C; putting the materials on a colloid mill; putting semi-finished products after grinding in a container to be cooled to normal temperature; metering and packaging the products after sampling inspection is qualified; and obtaining finished products of the humic acid-containing concentrated liquid compound fertilizer. The products have simple production process and low costs of raw materials and production, and can provide nutrition for the growth of crops, prevent and treat physiological diseases of the crops, and simultaneously ensure production increase of the crops and income increase of farmers.